Zoology and wildlife conservation

Explanation for fracture spacing in layered materials

Article Abstract:

A three-layer model can be used to analyze the stress distribution between two adjacent opening-mode fractures as a function of the fracture-spacing-to-layer-thickness ratio based on the entire set of governing equations for the elastic boundary-value problem. This research involved introducing four fractures in the fractured central layer, which is bonded to the adjacent layers. It was found that stress-transfer theory alone does not predict the stress-state transition. It is suggested that the stress-transfer theory should not be used in future studies of fracture spacing in layered materials.

An explanation for the central stress minimum in sand piles

Article Abstract:

The fixed principal axes hypothesis explains the minimum weight exerted by a conical sand pile below the apex by assuming that the principal stress axes have a fixed angle of inclination to the vertical. This assumption is used to close the equations of the continuum-mechanical theory in two dimensions. A second closure is necessary for three dimensions but the closure is unaffected by the assumptions made. This indicates that the propagation of stress is according to local rules that depend on the construction of the piles.

Bromination is used to manufacture bulk and fine chemicals, and the method uses elemental bromine, which is a pollutant and a health hazard. Haloperoxidase enzymes have inspired attempts to develop alternative and more benign methods. Vanadium bromoperoxidase is of particular interest. A tungstate-exchange layered double hydroxide catalyzing oxidative bromination and bromide-assisted epoxidation reactions selectively, is described. The catalyst is found to be more than 100 times active compared to its homogeneous analogue.